582 E. BLACKWELDBR GEOIX)GY OF WASATCH MOUNTAINS, UTAH 



Taken together, these facts of distribution and relation are suggestive 

 of an unconformity truncating the Weber quartzite and Morgan forma- 

 tions and going down into the Mississippian limestone. 



Further light on this question is furnished by the contact relations 

 between the Weber and Park City formations. In Weber Canyon and 

 several adjacent localities this contact is fairly well exposed. The excel- 

 lent section in Tunnel Hollow may be taken as typical. There the black 

 shale and limestone of the Park City formation grades downward into 

 alternate reddish sandstone, lavender and buff calcareous shales, and 

 finally into soft, massive white sandstone, with small concretions of 

 limonite. At the base of this white sandstone there is found nearly every- 

 where a hard quartzitic breccia which contains angular fragments of 



Beaver Creek 



Three sections 

 in slopes of Spring Canyon 



Sheephera 

 Creek 



r il in j p 



g.^^ fc 



III 



1. 1 . 1,1 



T-^^T- 



. » , w . m 



TTT 



II I 



^^=^F-^^ 





- ^ N' t= 





1 1 1 1 





1 1 1 1 





1 1 1 1 



III 



= N^ 1^ ^ 



I I I 



1 , 1.1 



III 



Pennsylvanian 

 sandstone 



Unconformity ? 



Mississippian 

 limestone 



1 



Figure 3. — Sections of the mid-Oarhoniferous Strata in the upper Valley of Ogden River 



Showing variation in tlie horizon of the Pennsylvanian sandstone. The shale with 

 nodules contains the late Mississippian fossils 



white chert, gray quartzite, and black chert, in the order given. One 

 chert fragment proved to be a worn specimen of a horn-coral, silicified. 

 This breccia rests with slightly undulating contact upon pale gray quartz- 

 ite, which is continuous with the body of the Weber quartzite. The con- 

 tact slowly truncates the individual layers of the quartzite below. On 

 the contact surface there is no accumulation of soil or the products of 

 weathering ; it is swept clean. Here and there, however, open fissures in 

 the quartzite are filled with wedges of the chert breccia. 



At another exposure of the contact, just west of Eobison's ranch, the 

 breccia is thicker and contains some water-worn material and a few 

 boulders as much as IS"* inches in diameter. There, also, fragments of 

 quartzite clearly predominate over the other constituents. 



In Big Cottonwood Canyon, near Salt Like City, the writer measured 

 somewhat roughly a section just north of the Wasatch Planting Station 

 of the Forest Service, in the upper part of the canyon. In this section 



